I love it when something that is being done for good reasons turns out to also have positive side-effects rather than negative ones. Municipalities around the world have been switching their street lights from sodium-vapor lamp - which emit a very yellow/orange light - to LED lamps, which are more energy efficient and last longer, reducing energy and maintenance costs... These lamps also happen to produce light of a more natural color. This, according to a new study by the University of Granada (UGR), has the benefit of making pedestrians feel safer at night.

To determine this, researchers from the Civil Engineering and Social Psychology at the UGR gave a test to 275 pedestrians who had just walked along streets illuminated by different types of streetlights to gauge their perceived safety and well-being. One of the potential reasons for the higher perceived safety might be that it is easier to identify human faces under the more natural lighting conditions.

Buenos Aires is an example of a city that decided to go big with LED streetlights that have a very different color temperature than the sodium-vapor lamps that they are replacing. The city had plans to change 100,000 of them a few years ago. Here's before: